1. Technical Field of the Invention
The present invention relates to data communications equipment and, in particular, to an input/output module providing both optical and electrical signal connectivity for interface use in communications equipment such as a router or switch.
2. Description of Related Art
The primary land-based signal transmission medium of the telephone/data communications system infrastructure is the copper wire transmission medium comprising, for example, a coaxial cable or a twisted wire pair. All communications signals, and in particular high speed digital signals, are more efficiently, accurately and consistently transmitted over an optical transmission medium such as a fiber optic cable. Accordingly, emphasis is currently being placed by communications providers on replacing copper wire cables with fiber optic cables.
Until replacement is completed and an all-fiber communications network is established, the communications system infrastructure must continue to facilitate the coexistence of the optical and electrical signal transmission media provided by fiber optic and copper wire communications links. One aspect of this coexistence is the conversion of digital communications signals between the optical pulses handled by the fiber optic media and the electrical pulses handled by the copper wire media. Another aspect of this coexistence is to provide for the switching (i.e., routing) of the optically transmitted digital signals carried by optical media to a desired destination over either optical or electrical media.
The conversion between optically and electrically transmitted signals is currently being performed by stand-alone fiber optic interface units that are installed separate from the other pieces of conventional electrical communications equipment that handles, for example, the switching of electrically transmitted signals. Such separate, stand-alone conversion units, however, inefficiently require extra space, power and cost. Accordingly, there is a need to incorporate the signal conversion functionality into certain pieces of communications equipment, and especially into communications system routers or switches.